a) The enzyme which transfers long chain fatty acids from acyl coenzyme A to rhodopsin has been solubilized and characterized. This newly discovered enzyme mediates a new class of posttranslational modification of membrane proteins, including receptors. b) A method has been developed to assess inositide metabolism in small amounts of tissue. In the rat pineal gland, the stimulatory effect of beta-adrenergic agents are potentiated by alpha-adrenergic stimulation. Lithium, at therapeutic doses, potentiates the effect of alpha stimulation, while having no effect on its own. Inositide metabolism is concomitantly affected. Phorbol esters mimic the effect of alpha-adrenergic stimulation. c) Lithium stimulates ACTH secretion by anterior pituitary cells in culture and by pituitary tumor (AtT-20) cells. Inositide metabolism is concomitantly affected. Lithium desensitizes the cells to subsequent stimulation by lithium or by phorbol esters, but not by other agonists.